(1) Field of the Invention
The invention relates to a device for detecting the profile depth and/or profile type of a vehicle tire and the ground clearance of vehicles in motion.
(2) Prior Art
To increase traffic safety and to collect fines, in past decades various technical devices have been invented and used in practice. In overview, these are speed measurement, distance measurement, weight monitoring, turning monitoring, traffic-light monitoring, belt monitoring and monitoring of alcohol level in the blood of the driver. Due to the high influence of the set of tyres on the driving physics of a motor vehicle, the set of tyres is measured within the framework of technical inspections and if there is an infringement, a fine is issued. Since 2006, the type of set of tyres is likewise checked, if it is not adapted to the season, the driver is cautioned by means of a fine.
The tyres of HGVs, private cars, motorcycles—simply all driven vehicles—are subject to wear. Below a minimum profile depth fixed by the legislator, a fine must be paid, because driving safety is no longer guaranteed using such a tyre. In Germany, set of tyres obligation is regulated in §36 StVZO. Essentially this provision states the following:
The profile must be at least 1.6 mm over the entire tread. The main profile (about ¾ of the tyre width) must have at least 1.6 mm profile depth and profile grooves must be present everywhere.
Pneumatic tyres must be provided with profile grooves or recesses on the entire periphery and on the whole width of the tread.
The wide profile grooves in the central region of the tread, which occupies about ¾ of the tread, apply as the main profile.
The part of the tyre which comes into contact with the roadway when travelling in a straight line is to be understood as the tread.
Expressed in examples, this means the following according to current administration of justice:                The minimum profile depth must be reached on ¾ of the tyre width. The two remaining ⅛ tyre widths may also have less than 1.6 mm profile depth, but must still have profile grooves.        A tyre has in the centre (¾ of the tyre width) 2.0 mm profile depth and at the outermost edge only 1.0 mm profile depth. This tyre is still according to regulation.        A tyre has on one edge still 6 mm profile depth, in the centre still 3 mm profile depth and on the opposite side is a 5 mm wide strip without any profile grooves. This tyre is to be queried.        
The difficulties when applying these provisions do not lie in the implementation, but in the fact that they are not adhered to or regularly checked by the vehicle owners and drivers.
In practice, adherence to these provisions is checked for the motor vehicles, for example by the following measures:                Prescribed regular main investigations        Vehicle monitoring by local regulatory authorities.        
However, the monitoring density is so low that—depending on investigation—3% to 7% of all motor vehicles in the Federal Republic of Germany are driven using incorrect tyres.
In practice this means that on a much driven road with, for example 50,000 vehicles per day, between 1,500 and 3,500 vehicles drive which do not have the correct set of tyres.
Checking an HGV having, for example 14 tyres, within the framework of police monitoring for profile depth, is expensive and takes up to 20 minutes.
Manual monitoring of all vehicles is certainly not practicable.
Within the framework of the following laid-open publications, automated measurement of pneumatic tyres and their profiles has been dealt with:
DE 2 900 040 C2
DE 4 316 984 A1
DE 4 101 921 A1
DE-OS 2 206 743
DE-OS 1 809 459
DE 29 508 978 U1
DE 94 11 617 U1
DE 83 04 751 U1
DE-GM 76 40 078
DE 69 113 712 T2
DE 19 744 076 A1
U.S. Pat. No. 3,918,816
WO 96 37 754 A1
WO 96 10 727 A1
Inter alia, camera detection of vehicles has been dealt with in the following publications:
DE 000069720022 T2
DE 000069418039 T2
In particular in DE 19 744 076 A1, the use of automatic profile-measuring apparatuses for determining the profile depths of pneumatic tyres is dealt with.
Publication DE 4 316 984 A1 describes the measurement of tyre profiles using laser light and an optical triangulation process.
A device according to the preamble of claim 1 is described in DE-OS 1 809 459.
Furthermore, DE 69 113 712 T2 discloses a device for determining the wear status of vehicle pneumatic tyre when it passes a predetermined path.
Use of a profile-measuring technique in flowing traffic cannot be realised using the technology described hitherto.
In detail, the following points are thus not to be regarded as solved:                The practical use in flowing traffic.        The protection of the environment, safety standards, danger to people due to the measuring device.        The fact that speeds of 10 km/hour-100 km/hour are conventional and measurements have to be made at these speeds.        The fact that the profile depth cannot be measured in bend situations or steering situations.        Issuing of a fine or the display of warning information for the particular traffic participant.        Identification of the tyre type (summer tyres/winter tyres) in flowing traffic.        
The problem underlying the invention is to provide a measuring system which solves the points listed and thus to provide a measuring system which detects the profile depth and the type of set of tyres (summer tyres/winter tyres) of pneumatic tyres in flowing traffic.